unreasonable
Americanadjective
-
not reasonable or rational; acting at variance with or contrary to reason; not guided by reason or sound judgment; irrational.
an unreasonable person.
-
not in accordance with practical realities, as attitude or behavior; inappropriate.
His Bohemianism was an unreasonable way of life for one so rich.
- Synonyms:
- nonsensical, stupid, absurd, preposterous, silly, foolish, senseless
-
excessive, immoderate, or exorbitant; unconscionable.
an unreasonable price; unreasonable demands.
- Synonyms:
- extravagant
-
not having the faculty of reason.
adjective
-
immoderate; excessive
unreasonable demands
-
refusing to listen to reason
-
lacking reason or judgment
Other Word Forms
Etymology
Origin of unreasonable
First recorded in 1300–50, unreasonable is from the Middle English word unresonabel. See un- 1, reasonable
Explanation
To be unreasonable means acting in an irrational way. Your expectation that your favorite team will win the Super Bowl every year is unreasonable. When someone's unreasonable, they're not using reason, or common sense, to make decisions or demands. Add the prefix un- to reasonable, "having sound judgment," and you get an adjective that's perfect for describing illogical behavior. It's often used for a certain kind of demanding stubbornness too: "It's completely unreasonable to make your server take your soup back five times to warm it up a little more."
Vocabulary lists containing unreasonable
"The Southpaw"
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Chronically Dolores
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Part 3 Vocabulary (Unit 2)
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The plaintiffs argue “excessive and unsustainable” pumping by the state Department of Water Resources constitutes a “wasteful and unreasonable use of water.”
From Los Angeles Times ● Oct. 9, 2026
She said it isn’t unreasonable and wanted me to consider her offer.
From MarketWatch ● Oct. 9, 2026
If the price of froyo seems unreasonable or if you can’t justify queueing for hours, BBC Food have five different froyo variations you can make at home.
From BBC ● Oct. 6, 2026
Expecting the modern, single-camera version of “A Different World” to recapture the multi-camera original’s magic is unreasonable.
From Salon ● Sep. 24, 2026
If a star could collapse to such a small size, it is not unreasonable to expect that other stars could collapse to even smaller size and become black holes.
From "A Brief History of Time: And Other Essays" by Stephen Hawking
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Get a wordDefinitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
